Abnormality determination device and abnormality determination method of vehicle

ABSTRACT

An abnormality determination device and an abnormality determination method of a vehicle that includes a stepped type automatic transmission capable of forming a plurality of speed change steps are provided. The presence/absence of an abnormality of an element related to formation of a predetermined speed change step is determined in a state of the vehicle where the predetermined speed change step is formed. Information about the abnormality determined to be present is then stored. If the information about the abnormality is stored when the vehicle is to newly start to run, the predetermined speed change step where the abnormality stored occurred is established, and the presence/absence of the abnormality of the element related to the formation of the predetermined speed change step is re-determined.

This is a Continuation Application of application Ser. No. 11/653,401filed Jan. 16, 2007, the entire disclosure of the prior application ishereby incorporated by reference herein in its entirety.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Applications No. 2006-021830 filed onJan. 31, 2006, including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an abnormality determination device and anabnormality determination method of a vehicle equipped with a steppedtype automatic transmission. More particularly, the invention relates toa technology that performs abnormality determination regarding elementsthat are related to formation of a predetermined speed change step.

2. Description of the Related Art

In a vehicle equipped with a stepped type automatic transmission capableof forming a plurality of speed change steps, a known abnormalitydetermination device determines whether or not the stepped typeautomatic transmission can normally form a speed change step.

For example, Japanese Patent Application Publication No. JP-A-2001-50382describes a failure detection device in conjunction with a planetarygear type automatic transmission in which the switching among the speedchange steps is performed by controlling the fastening (engagement) andrelease of a plurality of engagement devices. This failure detectiondevice of the automatic transmission includes abnormality determinationmeans for intentionally outputting a signal that causes the fastening ofan engagement device that normally must not be fastened for a gear step,that is, an engagement device other than the engagement devices selectedas a combination of devices to be fastened for the gear step, and fordetermining whether a fail-safe device that prevents interlock(simultaneous engagement) of the automatic transmission is reliablyoperating on the basis of whether or not pressure has been transmittedto the engagement device that normally must not be fastened.

Incidentally, in general, as for abnormalities due to valve sticking(valve fixation) of a fail-safe valve, a control valve, etc., orabnormalities of a detection switch that detects the pressuretransmitted to engagement devices, etc., the abnormality determinationneeds to be performed in a state where a speed change step has actuallybeen formed, or in a state where a command to form a speed change stephas been output as shown in Japanese Patent Application Publication No.JP-A-2001-50382.

Then, in the case where there is an abnormality, such as the valvesticking or the like, which cannot be detected unless a speed changestep has actually been formed, the shift to the speed change step havingthe abnormality may possibly be performed despite the abnormalitythereof; thus, there is a possibility of deterioration of thedrivability. Particularly, a high speed-side speed change step, which isless frequently used than a low speed-side speed change step, usuallyrequires a relatively long time for the abnormality determination andthe normality return determination, thus leading to a possibility ofeven greater deterioration of the drivability.

SUMMARY OF THE INVENTION

In light of the aforementioned problem, there are provided anabnormality determination device and an abnormality determination methodof a vehicle equipped with a stepped type automatic transmission capableof forming a plurality of speed change step which both improve thedrivability by appropriately determining the occurrence of anabnormality that cannot be detected unless a speed change step hasactually been formed.

Accordingly, an abnormality determination device of a vehicle thatincludes a stepped type automatic transmission capable of forming aplurality of speed change steps is provided. This determination deviceincludes the following devices:

an abnormality determiner that determines presence/absence of anabnormality of an element related to formation of a predetermined speedchange step in a state of the vehicle where the predetermined speedchange step is formed;

a storage device that stores information about the abnormalitydetermined to be present by the abnormality determiner; and

a controller that establishes, if the information about the abnormalityis stored in the storage means when the vehicle is to newly start torun, the predetermined speed change step where the abnormality storedoccurred, in order to cause re-determination of the presence/absence ofthe abnormality of the element related to the formation of thepredetermined speed change step.

According to another aspect of the invention, an abnormalitydetermination method of a vehicle that includes a stepped type automatictransmission capable of forming a plurality of speed change steps isprovided. This determination method includes:

determining presence/absence of an abnormality of an element related toformation of a predetermined speed change step in a state of the vehiclewhere the predetermined speed change step is formed;

storing information about the abnormality determined to be present; and

establishing, if the information about the abnormality is stored whenthe vehicle is to newly start to run, the predetermined speed changestep where the abnormality stored occurred, and re-determining thepresence/absence of the abnormality of the element related to theformation of the predetermined speed change step.

According to the abnormality determination device and the abnormalitydetermination method of the vehicle described above, if the informationabout an abnormality of an element related to the formation of apredetermined speed change step which was determined to be present bythe abnormality determiner is stored in the storage device when thevehicle is to newly start to run, the predetermined speed change step isestablished by the controller in order to cause re-determination of thepresence/absence of the abnormality of the element related to theformation of the predetermined speed change step. Therefore, theoccurrence of the abnormality that cannot be detected unless thepredetermined speed change step has actually been established can bedetermined before the vehicle runs on the predetermined speed changestep. Hence, for example, if the abnormality exists, the fail-safeoperation of prohibiting the shift to the predetermined speed changestep or the like can be performed. On the other hand, if normality hasreturned, the shift to the predetermined speed change step is allowed.Thus, the drivability can be improved.

In a suitable construction, the automatic transmission is constructed ofany of various planetary gear type multi-step transmissions having speedchange steps of, for example, forward four steps, forward five steps,forward six steps or more, in which one of a plurality of gear steps isselectively achieved as the rotating elements of a plurality of sets ofplanetary gear devices are selectively engaged, or a hybrid drive devicehas a configuration in which the automatic transmission includes adifferential mechanism constructed of, for example, a planetary geardevice, which distributes the motive power from an engine to a firstelectric motor and to an output shaft, and a second electric motorprovided on the output shaft of the differential mechanism, and thatmechanically transmits a major part of the motive power from the engineto the driving wheels and electrically transmits the remainder part ofthe motive power from the engine through the use of an electric pathfrom the first electric motor to the second electric motor so that thespeed change ratio is electrically altered, wherein the second electricmotor is operatively linked to the output shaft via the above-describedplanetary gear type multi-step transmission, or the like.

Furthermore, in a suitable construction, the installed posture of thetransmission relative to the vehicle may be a transversely mounted typein which the axis of the transmission is in the direction of width ofthe vehicle as in FF (front engine, front wheel drive) vehicles and thelike, or a longitudinally mounted type in which the axis of thetransmission is in the longitudinal direction of the vehicle as in FR(front engine, rear wheel drive) vehicles and the like.

In a suitable construction, as for the aforementioned frictionengagement devices, hydraulic friction engagement devices that areengaged by hydraulic actuators, including a multi-plate type orsingle-plate clutches or brakes, belt-type brakes, etc., are widelyused. The oil pump that supplies working oil for engaging the hydraulictype friction engagement devices may be, for example, a pump that isdriven by a motive power source for running the vehicle to eject theworking oil, or may also be a pump that is driven by a dedicatedelectric motor that is disposed separately from the vehicle-runningmotive power source. Besides, the clutches or brakes may also beelectromagnetic engage devices, for example, electromagnetic clutches,magnetic particle clutches, etc., besides hydraulic type frictionengagement devices.

Also, in a suitable construction, it is appropriate if the drive powersource, such as the engine, that is, an internal combustion engine suchas a gasoline engine, a diesel engine, etc., an electric motor, etc.,and the automatic transmission are operatively interlinked. For example,a pulsation absorption damper (vibration damping device), adirect-couple clutch, a damper-equipped direct-couple clutch, a fluidtransfer device, etc., may be disposed between therebetween. The drivepower source and the input shaft of the automatic transmission may alsobe always linked. As for the fluid transfer device, a lockupclutch-equipped torque converter, a fluid coupling, etc., are widelyused.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, advantages thereof, and technical and industrialsignificance of this invention will be better understood by reading thefollowing detailed description of preferred embodiments of theinvention, when considered in connection with the accompanying drawings,in which:

FIG. 1 is a diagram illustrating a hybrid drive device to which a firstembodiment as an example of the invention is applied, and is also ablock diagram illustrating portions of a control system that is providedin the vehicle for controlling the hybrid drive device and the like;

FIG. 2 is an alignment chart showing a relative relationship in rotationspeed among the rotating elements of a single-pinion type planetary geardevice that functions as a torque combining-distributing mechanism;

FIG. 3 is an alignment chart representing an interrelationship among therotating elements of Ravigneaux type planetary gear mechanism thatconstitutes a transmission;

FIG. 4 shows a shift-purpose hydraulic control circuit for automaticallycontrolling the shift of the transmission by engaging and releasing afirst brake and a second brake;

FIG. 5 is a diagram showing a valve characteristic of a normally closedtype first linear solenoid valve that establishes an open valve(communicated) state between the input port and the output port during anon-electrified state;

FIG. 6 is a diagram showing a valve characteristic of a normally opentype second linear solenoid valve that establishes a closed valve(shut-off) state between the input port and the output port during anon-electrified state;

FIG. 7 is a table illustrating operations of a hydraulic controlcircuit;

FIG. 8 is a functional block diagram illustrating portions of controlfunctions of electronic control devices shown in FIG. 1;

FIG. 9 is a shift chart that is used in a shift control of thetransmission performed by the electronic control devices shown in FIG.1;

FIG. 10 is a flowchart illustrating portions of the control operation ofthe electronic control devices shown in FIG. 1, that is, an abnormalitydetermination routine for performing abnormality determination regardinga high speed step, and is a subroutine corresponding to an abnormalitydetermination routine that is executed in a flowchart shown in FIG. 11;and

FIG. 11 is the flowchart illustrating portions of the control operationof the electronic control devices shown in FIG. 1, that is, a controloperation for abnormality determination regarding the high speed stepwhich is one of system checks that is executed at the time of start ofvehicle run.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description and the accompanying drawings, the presentinvention will be described in more detail with reference to exemplaryembodiments.

FIG. 1 is a diagram illustrating a hybrid drive device 10 to which afirst embodiment as an example of the invention is applied. Referring toFIG. 1, in the hybrid drive device 10, torque of a first drive source 12that is a main drive source is transmitted to an output shaft 14 thatfunctions as an output member, and the torque is transmitted from theoutput shaft 14 to a pair of left and right driving wheels 18 via adifferential gear device 16 in a vehicle. Besides, in the hybrid drivedevice 10, a second drive source 20 capable of selectively executing apower running control of outputting the drive power for running thevehicle or a regenerative control for recovering energy is provided. Thesecond drive source 20 is linked to the output shaft 14 via atransmission 22. Therefore, the capacity of torque transmitted from thesecond drive source 20 to the output shaft 14 is increased or decreasedin accordance with the speed change ratio γs (=the rotation speed of theMG2/the rotation speed of the output shaft 14) that is set by thetransmission 22.

The transmission 22 is constructed so as to establish a plurality ofsteps whose speed change ratios γs is greater than or equal to “1”.Therefore, at the time of power running when torque is output from thesecond drive source 20, the torque can be increased by the transmission22 while being transmitted to the output shaft 14. Hence, the seconddrive source 20 is constructed with a further reduced capacity or in afurther reduced size. Due to this, for example, in the case where therotation speed of the output shaft 14 increases in association with highvehicle speed, the speed change ratio γs is dropped to drop the rotationspeed of the second drive source 20, in order to maintain a good stateof the operation efficiency of the second drive source 20. In the casewhere the rotation speed of the output shaft 14 drops, the speed changeratio γs is increased.

As for the shifting of the transmission 22, the torque capacity of thetransmission 22 drops or inertial torque associated with change in therotation speed occurs, in which case the torque of the output shaft 14,that is, the output shaft torque, is affected. Therefore, in the hybriddrive device 10, on the occasion of shifting by the transmission 22, acontrol is performed such that the torque of the first drive source 12is corrected so as to prevent or restrain the torque fluctuation of theoutput shaft 14.

The first drive source 12 is constructed mainly of an engine 24, a MG1(hereinafter, referred to as “MG1”), and a planetary gear device 26provided for combining or distributing torque between the engine 24 andthe MG1. The engine 24 is a publicly known internal combustion enginethat outputs power by burning fuel, such as a gasoline engine, a dieselengine, etc. The engine 24 is constructed so that states of operationthereof, such as a the throttle opening degree, the intake air amount,the fuel supply amount, the ignition timing, etc., are electricallycontrolled by an engine-controlling electronic control device (E-ECU) 28that is made up mainly of a microcomputer. The electronic control device28 is supplied with detection signals from an accelerator operationamount sensor AS that detects the operation amount of an acceleratorpedal 27, a brake sensor BS for detecting operation of a brake pedal 29,etc.

The MG1 is, for example, a synchronous electric motor, and isconstructed to selectively perform the function as an electric motor ofgenerating drive torque and the function as an electric power generator.The MG1 is connected to an electricity storage device 32, such as abattery, a capacitor, etc., via an inverter 30. Then, the inverter 30 iscontrolled by a motor-generator-controlling electronic control device(MG-ECU) 34 made up mainly of a microcomputer so that the output torqueof the MG1 or the regenerative torque is adjusted or set. The electroniccontrol device 34 is supplied with detection signals from an operationposition sensor SS that detects the operation position of a shift lever35, and the like.

The planetary gear device 26 is a single-pinion type planetary gearmechanism that includes three rotating elements: a sun gear S0, a ringgear R0 disposed concentrically with the sun gear S0, and a carrier C0that supports pinions P0 meshing with the sun gear S0 and the ring gearR0, in such a manner that the pinions P0 are rotatable about their ownaxes and also revolvable. The planetary gear device 26 causes knowndifferential effect. The planetary gear device 26 is providedconcentrically with the engine 24 and the transmission 22. Since theplanetary gear device 26 and the transmission 22 are constructedsubstantially symmetrically about a center line, the half portionsthereof below the center line are omitted in FIG. 1.

In this embodiment, a crankshaft 36 of the engine 24 is linked to thecarrier C0 of the planetary gear device 26 via a damper 38. The sun gearS0 is linked to the MG1, and the output shaft 14 is linked to the ringgear R0. The carrier C0 functions as an input element, and the sun gearS0 functions as a reaction force element, and the ring gear R0 functionsas an output element.

Relative relationships among the rotating elements of the single-piniontype planetary gear device 26 that functions as a torquecombining-distributing mechanism are shown by an alignment chart in FIG.2. In the alignment chart, a vertical axis S, a vertical axis C, and avertical axis R represent the rotation speed of the sun gear S0, therotation speed of the carrier C0, and the rotation speed of the ringgear R0, respectively. The intervals between the vertical axis S, thevertical axis C, and the vertical axis R are set so that when theinterval between the vertical axis S and the vertical axis C is 1, theinterval between the vertical axis C and the vertical axis R becomes p(the number of teeth Zs of the sun gear S0/the number of teeth Zr of thering gear R0).

In the planetary gear device 26, when a reaction torque from the MG1 isinput to the sun gear S0 while the output torque of engine 24 is inputto the carrier C0, a torque greater than the torque input from theengine 24 appears on the ring gear R0 that is the output element, sothat the MG1 functions as an electric power generator. While therotation speed of the ring gear R0 (output shaft rotation speed) NO isconstant, the rotation speed NE of the engine 24 can be continuously(steplessly) changed by changing the rotation speed of the MG1 upward ordownward. The dashed line in FIG. 2 shows a state where the rotationspeed NE of the engine 24 drops when the rotation speed of the MG1 islowered from the value shown by a solid line. That is, a control ofsetting the rotation speed NE of the engine 24 at, for example, arotation speed that provides the best fuel economy, can be executed bycontrolling the MG1. This type of hybrid system is termed mechanicaldistribution system or split type.

Referring back to FIG. 1, the transmission 22 of the embodiment isconstructed of one set of a Ravigneaux type planetary gear mechanism.Specifically, in the transmission 22, a first sun gear S1 and a secondsun gear S2 are provided, and short pinions P1 mesh with the first sungear S1. The short pinions P1 also mesh with long pinions P2 whose axiallength is longer than that of the short pinions P1. The long pinions P2mesh with a ring gear R1 that is disposed concentrically with the sungears S1, S2. The pinions P1, P2 are supported by a common carrier C1 soas to be rotatable about their own axes and also revolvable. Besides,the second sun gear S2 meshes with the long pinions P2.

The second drive source 20 is constructed of a second motor-generator(hereinafter, referred to as “MG2”) that is an electric motor or anelectric power generator that is controlled by themotor-generator-controlling electronic control device (MG-ECU) 34 via aninverter 40 so that the assist-purpose output torque or the regenerativetorque is adjusted or set. The MG2 is linked to the second sun gear S2,and the carrier C1 is linked to the output shaft 14. The first sun gearS1 and the ring gear R1, together with the pinions P1, P2, construct amechanism that corresponds to a double-pinion type planetary geardevice. The second sun gear S2 and the ring gear R1, together with thelong pinions P2, construct a mechanism that corresponds to asingle-pinion type planetary gear device.

The transmission 22 is also provided with a first brake B1 that isprovided between the first sun gear S1 and a transmission housing 42 forselectively fixing the first sun gear S1, and a second brake B2 that isprovided between the ring gear R1 and the transmission housing 42 forselectively fixing the ring gear R1. These brakes B1, B2 are so-calledfriction engagement devices that produce braking force by frictionforce. As the brakes, it is possible to adopt multi-plate typeengagement devices or band-type engagement devices. Then, each of thebrakes B1, B2 is constructed so that the torque capacity thereofcontinuously changes in accordance with the engagement pressure that isgenerated by a hydraulic actuator or the like.

In the transmission 22 constructed as described above, when the secondsun gear S2 functions as an input element and the carrier C1 functionsas an output element and the first brake B1 is engaged, a high speedstep H whose speed change ratio γsh is greater than “1” is achieved. Ifthe second brake B2 is engaged instead of the first brake B1 in asimilar situation, a low speed step L whose speed change ratio γsl isgreater than the speed change ratio γsh of the high speed step H is set.The shifting between the speed change steps H and L is executed on thebasis of states of run of the vehicle such as the vehicle speed, therequired drive power (or the accelerator operation amount), etc. Moreconcretely, speed change step regions are determined beforehand as a map(shift chart), and a control is performed such as to set either one ofthe speed change steps in accordance with the detected vehicle drivingstate. A shift-controlling electronic control device (T-ECU) 44 made upmainly of a microcomputer for performing the control is provided.

The electronic control device 44 is supplied with detection signals froman oil temperature sensor TS for detecting the temperature of theworking oil, a hydraulic switch SW1 for detecting the engagement oilpressure of the first brake B1, a hydraulic switch SW2 for detecting theengagement oil pressure of the second brake B2, a hydraulic switch SW3for detecting the line pressure PL, etc.

FIG. 3 shows an alignment chart that has four vertical axes, that is, avertical axis S1, a vertical axis R1, a vertical axis C1, and a verticalaxis S2, in order to represent relative relationships between therotating elements of the Ravigneaux type planetary gear mechanism thatconstitutes the transmission 22. The vertical axis S1, the vertical axisR1, the vertical axis C1, and the vertical axis S2 show the rotationspeed of the first sun gear S1, the rotation speed of the ring gear R1,the rotation speed of the carrier C1, and the rotation speed of thesecond sun gear S2, respectively.

In the transmission 22 constructed as described above, when the ringgear R1 is fixed by the second brake B2, the low speed step L is set,and the assist torque that the MG2 outputs is amplified in accordancewith the corresponding speed change ratio γsl, and is thus applied tothe output shaft 14. On the other hand, when the first sun gear S1 isfixed by the first brake B1, the high speed step H having the speedchange ratio γsh that is smaller than the speed change ratio γhl of thelow speed step L is set. Since the speed change ratio of the high speedstep H is also larger than “1”, the assist torque that the MG2 outputsis amplified in accordance with the speed change ratio γsh, and isapplied to the output shaft 14.

Incidentally, although the torque applied to the output shaft 14 duringa state where one of the speed change steps L, H is steadily set is atorque obtained by increasing the output torque of the MG2 in accordancewith the corresponding speed change ratio, the torque during a shifttransitional state of the transmission 22 is a torque that is affectedby the torque capacity at the brake B1 or B2, the inertia torqueassociated with the rotation speed change, etc. Besides, the torqueapplied to the output shaft 14 becomes positive torque during a drivingstate of the MG2, and becomes negative torque during a driven state ofthe MG2.

FIG. 4 shows a shift-purpose hydraulic control circuit 50 forautomatically controlling the shifting of the transmission 22 byengaging and releasing the brakes B1, B2. The hydraulic control circuit50 includes, as oil pressure sources, a mechanical type hydraulic pump46 that is operatively linked to the crankshaft 36 of the engine 24 andtherefore is rotationally driven by the engine 24, and an electric typehydraulic pump 48 that includes an electric motor 48 a and a pump 48 bthat is rotationally driven by the electric motor 48 a. The mechanicaltype hydraulic pump 46 and the electric type hydraulic pump 48 suck theworking oil that is refluxed to an oil pan (not shown), via a strainer52, or suck the working oil that is directly refluxed via a reflux oilpassageway 53, and pumps the working oil to a line pressure oilpassageway 54. An oil temperature sensor TS for detecting the oiltemperature of the refluxed working oil is provided on a valve body 51that partially forms the hydraulic control circuit 50, but may also beconnected to a different site.

A line pressure regulating valve 56 is a relief-type pressure regulatingvalve, and includes a spool valve element 60 that opens and closesbetween a supply port 56 a connected to the line pressure oil passageway54 and a discharge port 56 b connected to a drain oil passageway 58, acontrol oil chamber 68 which houses a spring 62 that generates thrust inthe closing direction of the spool valve element 60 and which receives amodule pressure PM from a module pressure oil passageway 66 via anelectromagnetic open-close valve 64 when the set pressure of the linepressure PL is altered to a higher level, and a feedback oil chamber 70connected to the line pressure oil passageway 54 which generates thrustin the opening direction of the spool valve element 60. The linepressure regulating valve 56 outputs a constant line pressure PL that isone of a low pressure and a high pressure. The line pressure oilpassageway 54 is provided with a hydraulic switch SW3 that is in anoff-state when the line pressure PL is at the high pressure-side value,and that is in an on-state when the line pressure PL is at the lowpressure-side value or lower. Since the operation of the hydraulicswitch SW3 is switched depending of the high or low level of the linepressure PL, it is possible to determine the presence/absence of anabnormality of the line pressure regulating valve 56 as well as thepresence/absence of an abnormality of the line pressure PL.

A module pressure regulating valve 72 outputs to the module pressure oilpassageway 66 a constant module pressure PM that is set lower than thelow pressure-side line pressure PL, using the line pressure PL as abasic pressure, regardless of fluctuations of the line pressure PL. Afirst linear solenoid valve SLB1 for controlling the first brake B1 anda second linear solenoid valve SLB2 for controlling the second brake B2,using the module pressure PM as a basic pressure, output controlpressures PC1 and PC2 in accordance with drive currents ISOL1 and ISOL2that are command values from the electronic control device 44.

The first linear solenoid valve SLB1 has a normally open type valvecharacteristic of establishing an open valve (communicated) statebetween the input port and the output port during the non-electrifiedstate. As shown in FIG. 5, as the drive current ISOL1 increases, theoutput control pressure PC1 is dropped. As shown in FIG. 5, the valvecharacteristic of the first linear solenoid valve SLB1 is provided witha dead band A in which the output control pressure PC1 does not dropuntil the drive current ISOL1 exceeds a predetermined value Ia. Thesecond linear solenoid valve SLB2 has a normally closed type valvecharacteristic of establishing a closed (shut-off) state between theinput port and the output port during the non-electrified state. Asshown in FIG. 6, as the drive current ISOL2 increases, the outputcontrol pressure PC2 is increased. As shown in FIG. 6, the valvecharacteristic of the second linear solenoid valve SLB2 is provided witha dead band B in which the output control pressure PC2 does not increaseuntil the drive current ISOL2 exceeds a predetermined value Ib.

A B1 control valve 76 includes a spool valve element 78 that opens andcloses between an input port 76 a connected to the line pressure oilpassageway 54 and an output port 76 b that outputs a B1 engagement oilpressure PB1, a control oil chamber 80 that receives the controlpressure PC1 from the first linear solenoid valve SLB1 in order to urgethe spool valve element 78 in the opening direction, and a feedback oilchamber 84 which houses a spring 82 that urges the spool valve element78 in the closing direction and which receives the B1 engagement oilpressure PB1 that is the output pressure. The B1 control valve 76, usingthe line pressure PL in the line pressure oil passageway 54 as a basicpressure, outputs the B1 engagement oil pressure PB1 whose magnitude isin accordance with the control pressure PC1 from the first linearsolenoid valve SLB1, and supplies it to the brake B1 through a B1 applycontrol valve 86 that functions as an interlock valve.

A B2 control valve 90 includes a spool valve element 92 that opens andcloses between an input port 90 a connected to the line pressure oilpassageway 54 and an output port 90 b that outputs a B2 engagement oilpressure PB2, a control oil chamber 94 that receives the controlpressure PC2 from the second linear solenoid valve SLB2 in order to urgethe spool valve element 92 in the opening direction, and a feedback oilchamber 98 which houses a spring 96 that urges the spool valve element92 in the closing direction and which receives the B2 engagement oilpressure PB2 that is the output pressure. The B2 control valve 90, usingthe line pressure PL in the line pressure oil passageway 54 as a basicpressure, outputs the B2 engagement oil pressure PB2 whose magnitude isin accordance with the control pressure PC2 from the second linearsolenoid valve SLB2, and supplies it to the brake B2 through a B2 applycontrol valve 100 that functions as an interlock valve.

The B1 apply control valve 86 includes a spool valve element 102 whichopens and closes an input port 86 a that receives the B1 engagement oilpressure PB1 output from the B1 control valve 76 and an output port 86 bconnected to the first brake B1, an oil chamber 104 that receives themodule pressure PM in order to urge the spool valve element 102 in theopening direction, and an oil chamber 108 which houses a spring 106 thaturges the spool valve element 102 in the closing direction and whichreceives the B2 engagement oil pressure PB2 output from the B2 controlvalve 90. The B1 apply control valve 86 is held in the open valve stateuntil it is supplied with the B2 engagement oil pressure PB2 forengaging the second brake B2. When the B2 engagement oil pressure PB2 issupplied, the B1 apply control valve 86 is switched to the closed valvestate, so that the engagement of the first brake B 1 is prevented.

The B1 apply control valve 86 is provided with a pair of ports 110 a and110 b that are closed when the spool valve element 102 is in the openvalve position (position as indicated on the right side of a center lineshown in FIG. 4), and that are opened when the spool valve element 102is in the valve closed position (position as indicated on the left sideof the center line shown in FIG. 4). The hydraulic switch SW2 fordetecting the B2 engagement oil pressure PB2 is connected to the port110 a, and the second brake B2 is directly connected to the other port110 b. The hydraulic switch SW2 assumes an on-state when the B2engagement oil pressure PB2 becomes a high-pressure state that is setbeforehand, and is switched to an off-state when the B2 engagement oilpressure PB2 reaches or goes below a low-pressure state that is setbeforehand. Since the hydraulic switch SW2 is connected to the secondbrake B2 via the B1 apply control valve 86, it is possible to determinethe presence/absence of an abnormality of the first linear solenoidvalve SLB1, the B1 control valve 76, the B1 apply control valve 86,etc., that constitute the hydraulic system of the first brake B1, aswell as the presence/absence of an abnormality of the B2 engagement oilpressure PB2.

The B2 apply control valve 100, similar to the B1 apply control valve86, includes a spool valve element 112 that opens and closes between aninput port 100 a that receives the B2 engagement oil pressure PB2 outputfrom the B2 control valve 90 and an output port 100 b connected to thesecond brake B2, an oil chamber 114 that receives the module pressure PMin order to urge the spool valve element 112 in the opening direction,and an oil chamber 118 which houses a spring 116 that urges the spoolvalve element 112 in the closing direction and which receives the B1engagement oil pressure PB1 output from the B1 control valve 76. The B2apply control valve 100 is held in the open valve state until it issupplied with the B1 engagement oil pressure PB1 for engaging the firstbrake B1. When the B1 engagement oil pressure PB1 is supplied, the B2apply control valve 100 is switched to the closed valve state, so thatthe engagement of the second brake B2 is prevented.

The B2 apply control valve 100 is also provided with a pair of parts 120a and 120 b that are closed when the spool valve element 112 is in theopen valve position (position as indicated on the right side of a centerline shown in FIG. 4), and that are opened when the spool valve element112 is in the valve closed position (position as indicated on the leftside of the center line shown in FIG. 4). The hydraulic switch SW1 fordetecting the B1 engagement oil pressure PB1 is connected to the port120 a, and the first brake B1 is directly connected to the other port120 b. The hydraulic switch SW1 assumes an on-state when the B1engagement oil pressure PB1 becomes a high-pressure state that is setbeforehand, and is switched to an off-state when the B1 engagement oilpressure PB1 reaches or goes below a low-pressure state that is setbeforehand. Since the hydraulic switch SW1 is connected to the firstbrake B1 via the B2 apply control valve 100, it is possible to determinethe presence/absence of an abnormality of the second linear solenoidvalve SLB2, the B2 control valve 90, the B2 apply control valve 100,etc., that constitute the hydraulic system of the second brake B2, aswell as the presence/absence of an abnormality of the B1 engagement oilpressure PB1.

FIG. 7 is a table illustrating operations of the hydraulic controlcircuit 50 constructed as described above. In FIG. 7, symbol “◯” showsthe excited state or the engaged state, and symbol “×” shows thenon-excited state or the released state. That is, by putting both thefirst linear solenoid valve SLB1 and the second linear solenoid valveSLB2 into the excited state, the first brake B1 is put into the releasedstate and the second brake B2 is put into the engaged state, so that thelow speed step L (i.e., the first speed gear step) of the transmission22 is achieved. By putting both the first linear solenoid valve SLB1 andthe second linear solenoid valve SLB2 into the non-excited state, thefirst brake B1 is put into the engaged state and the second brake B2 isput into the released state, so that the high speed step H (i.e., thesecond speed gear step) of the transmission 22 is achieved.

FIG. 8 is a functional block diagram illustrating portions of controlfunctions of the electronic control devices 28, 34 and 44. In FIG. 8,for example, when the control is activated as the power switch isoperated during a state where the brake pedal is operated after the keyhas been inserted into the key slot, a hybrid drive control device 130calculates a driver's requested output on the basis of the acceleratoroperation amount, and causes the engine 24 and/or the MG2 to generatethe requested output so as to bring about an operation with good fueleconomy and low emission gas amount. For example, the run mode isswitched in accordance with the state of run of the vehicle, among amotor run mode in which the engine 24 is stopped and the MG2 is solelyused as drive source, a run mode in which the vehicle is run by usingthe MG2 as a drive source while electric power is generated from themotive power of the engine 24, and an engine run mode in which thevehicle is run by mechanically transmitting the motive power of theengine 24 to the driving wheels 18.

The hybrid drive control device 130 controls the rotation speed of theengine 24 via the MG1 so that the engine 24 operates on an optimal fueleconomy curve, even when the engine 24 is driven. Besides, in the casewhere the MG2 is driven to perform the torque assist, the hybrid controldevice 130 sets the transmission 22 to the low speed step L to increasethe torque applied to the output shaft 14 during a state of low vehiclespeed. During a state of increased vehicle speed, the hybrid controldevice 130 sets the transmission 22 to the high speed step H torelatively drop the rotation speed of the MG2 and therefore reduce theloss. Thus, the torque assist with good efficiency is executed.Furthermore, during the coasting run, the inertia energy that thevehicle has is used to rotationally drive the MG1 or the MG2, so thatthe energy is regenerated as electric power that is in turn stored intothe electricity storage device 32.

A shift control device 132 determines a speed change step of thetransmission 22 on the basis of the speed V and the drive power P of thevehicle from a pre-stored shift chart, for example, as shown in FIG. 9,and outputs the drive currents ISOL1 and ISOL2, i.e., the commandvalues, to the hydraulic control circuit 50 to control the engagementand release of the first brake B1 and the second brake B2 so that theswitch to the determined speed change step is automatically performed.

In the case where the calculated driver's requested output is greaterthan a pre-set output criterion value, or in the case where thetransmission 22 is performing a shift, that is, is in a shift transitionstate, or the like, a line pressure control device 134 switches the setpressure of the line pressure PL from a low pressure state to a highpressure state by switching the electromagnetic open-close valve 64 fromthe closed state to the open state to supply the module pressure PM intothe oil chamber 68 of the line pressure regulating valve 56 and totherefore increase the thrust on the spool valve element 60 in theclosing direction by a predetermined value.

In the state of the vehicle in which either one of the speed changesteps L, H is formed, an abnormality determination device 136 determinesthe presence/absence of an abnormality of elements related to theformation of that speed change step L, H on the basis of, for example, apredetermined rule.

The elements related to the formation of the speed change steps L, Hinclude the line pressure regulating valve 56 that regulates the linepressure PL that serves as the basic pressure of, for example, the B1engagement oil pressure PB1, the B2 engagement oil pressure PB2, etc.,the first linear solenoid valve SLB1, the B1 control valve 76, the B1apply control valve 86, etc. that constitute the hydraulic system of thefirst brake B1, the second linear solenoid valve SLB2, the B2 controlvalve 90, the B2 apply control valve 100, etc. that constitute thehydraulic system of the second brake B2, the hydraulic switch SW1 fordetecting the B1 engagement oil pressure PB1, the hydraulic switch SW2for detecting the B2 engagement oil pressure PB2, the hydraulic switchSW3 for detecting the line pressure PL, etc. As for the abnormality ofthese elements, the valve sticking or the like is assumed with regard tothe aforementioned valves. With regard to the hydraulic switches SW1,SW2, SW3, the abnormality in the switching operation between theon-state and the off-state thereof or the like is assumed. With regardto the linear solenoid valves SLB1, SLB2, such abnormalities as a break,shortcircuit, etc. are assumed.

Thus, the presence/absence of an abnormality of the aforementionedindividual valves can be determined by detecting the states of operationof the hydraulic switches SW1, SW2, SW3, and the presence/absence of anabnormality of the individual switches SW1, SW2, SW3 themselves can alsobe determined. For example, in the case where the speed change step isswitched to the low speed step L, the normal state includes theoff-state of the switch SW1 corresponding to the pre-set low pressurestate of the B1 engagement oil pressure PB1 or a state below the pre-setlow pressure state, the on-state of the switch SW2 corresponding to thepre-set high pressure state of the B2 engagement oil pressure PB2, andthe on-state of the switch SW3 that detects the high pressure state,that is, the set pressure of the line pressure PL for the shifttransition time. Besides, when the speed change step is switched to thehigh speed step H, the normal state includes the on-state of the switchSW1 corresponding to the pre-set high pressure state of the B1engagement oil pressure PB1, the off-state of the switch SW2corresponding to the pre-set low pressure state of the B2 engagement oilpressure PB2 or a state below the pre-set low pressure state, and theon-state of the switch SW3 that detects the high pressure state, thatis, the set pressure of the line pressure PL for the shift transitiontime.

The abnormality determination device 136, for example, when the lowspeed step L has been established, determines whether or not the switchSW1 is in the off-state, and whether or not the switch SW2 is in theon-state, and whether or not the switch SW3 is in the on-state, on thebasis of a rule determined beforehand. If it is determined that theswitch SW1 is in the off-state, and the switch SW2 is in the on-state,and the switch SW3 is in the on-state, the abnormality determinationdevice 136 sets up a low-speed step normality determination flag FLG asa low-speed step determination flag FL. On the other hand, if theabnormality determination device 136 makes any one of the following: adetermination that the switch SW1 is in the on-state; a determinationthat the switch SW2 is in the off-state; and a determination that theswitch SW3 is in the off-state, the abnormality determination device 136sets up a low-speed step abnormality determination flag FLE as alow-speed step determination flag FL.

For example, when the high speed step H has been established, theabnormality determination device 136 determines whether or not theswitch SW1 is in the on-state, and whether or not the switch SW2 is inthe off-state, and whether or not the switch SW3 is in the on-state, onthe basis of a rule determined beforehand. If it is determined that theswitch SW1 is in the on-state, and the switch SW2 is in the off-state,and the switch SW3 is in the on-state, the abnormality determinationdevice 136 sets up a high-speed step normality determination flag FHG asa high-speed step determination flag FH. On the other hand, if theabnormality determination device 136 makes any one of the following: adetermination that the switch SW1 is in the off-state; a determinationthat the switch SW2 is in the on-state; and a determination that theswitch SW3 is in the off-state, the abnormality determination device 136sets up a high-speed step abnormality determination flag FHE as thehigh-speed step determination flag FH.

A storage device 138 stores information about the abnormality determinedto be present by the abnormality determination device 136. For example,the storage device 138 stores the low-speed step determination flag FLand the high-speed step determination flag FH while serially rewritingthem to the determination flags F that are set up by the abnormalitydetermination device 136.

A speed change step determination device 140 determines whether or notthe shift of the transmission 22 to the high speed step H has beenperformed, for example, on the basis of whether or not the commandvalues of the drive currents ISOL1 and ISOL2 for obtaining the highspeed step H via the shift control device 132 have been output to thehydraulic control circuit 50. Also, the speed change step determinationdevice 140 determines whether or not the shift of the transmission 22 tothe low speed step L has been performed, for example, on the basis ofwhether or not the commands of the drive currents ISOL1 and ISOL2 forobtaining the low speed step L via the shift control device 132 havebeen output to the hydraulic control circuit 50.

The fail-safe process device 142 performs the abnormality determinationon the basis of the determination flag F set up by the abnormalitydetermination device 136, and accordingly executes a fail-safe process.

For example, the fail-safe process device 142 determines the low-speedstep determination flag FL that has been set up by the abnormalitydetermination device 136. Then, if the low-speed step abnormalitydetermination flag FLE has been set up as the low-speed stepdetermination flag FL, the fail-safe process device 142 outputs to theshift control device 132 a command to prohibit the shift to the lowspeed step L as a fail-safe process. On the other hand, if the low-speedstep normality determination flag FLG has been set up as the low-speedstep determination flag FL, the fail-safe process device 142 does notoutput to the shift control device 132 the command to prohibit the shiftto the low speed step L as a normal-time process.

Also, the fail-safe process device 142 determines the high-speed stepdetermination flag FH that has been set up by the abnormalitydetermination device 136. Then, if the high-speed step abnormalitydetermination flag FHE has been set up as the high-speed stepdetermination flag FH, the fail-safe process device 142 outputs to theshift control device 132 a command to prohibit the shift to the highspeed step H as a fail-safe process. On the other hand, if thehigh-speed step normality determination flag FHG has been set up as thehigh-speed step determination flag FH, the fail-safe process device 142does not output to the shift control device 132 the command to prohibitthe shift to the high speed step H, as a normal-time process.

Thus, the determination as to the abnormality regarding the formation ofeach of the speed change steps L, H is carried out by actual performanceof the shift to the speed change step, and if the abnormalitydetermination is made, the fail-safe operation is then executed. Fromanother viewpoint, the abnormalities of valves, such as the B1 applycontrol valve 86 and the like, cannot be detected without actualformation of any speed change step. Therefore, in order for thefail-safe operation to be executed at the time of abnormalitydetermination, there is a need to perform the shift to each speed changestep L, H and perform the abnormality determination. Therefore, even ifan abnormality has occurred regarding a speed change step, the shift tothat speed change step may be performed once, and there is possibilityof deterioration of the drivability. Particularly, the high speed stepH, which is less frequently used than the low speed step L, usuallyrequires a relatively long time for the abnormality determination andthe normality return determination, and there is a possibility of evengreater deterioration of the drivability.

Hence, in order that the occurrence of an abnormality that cannot bedetected unless a speed change step has actually been formed will bedetermined before the vehicle runs on that speed change step, are-determination-purpose speed change step establishment device 144, ifinformation about an abnormality is stored in the storage device 138when the vehicle is to newly start to run, establishes the speed changestep where the abnormality stored in the storage device 138 occurred, inorder to cause the abnormality determination device 136 to re-determinethe presence/absence of an abnormality of an element related to theformation of the speed change step. Due to this, for example, in thecase where the abnormality is determined to be present, a fail-safeoperation of, for example, prohibiting the shift to that speed changestep, can be performed before the vehicle runs on the speed change step.On the other hand, in the case where the abnormality is not determinedto be present but normality has returned, the shift to that speed changestep can be performed. Thus, the drivability can be improved.

Hereinafter, the control operation of the re-determination-purpose speedchange step establishment device 144 will be concretely described.Incidentally, the following description will be made in conjunction withthe case of the high speed step H where there particularly is apossibility of deterioration of the drivability, as for example, and thedescription in conjunction with the case of the low speed step L will beomitted. Of course, what will be described below applies to the lowspeed step L as well.

A vehicle run start determination device 146 determines whether or not anew vehicle run starting operation has been performed, that is, whetheror not a user's operation for starting to run the vehicle has beenperformed, for example, on the basis of whether or not a power switchST_ON has been operated during a state where the brake pedal is operatedafter the on-operation with the key inserted in a key slot has beenperformed. It is to be noted herein that the vehicle run startingoperation includes the activating operation of the control device, andthe starting of a system check of a control device or the like forobtaining a ready-to-run state READY-ON (e.g., the abnormalitydetermination by the abnormality determination device 136), and does notmean the launch of the vehicle from the stopped state, as in the case ofa signal stop or the like. However, by subsequently operating the shiftlever 35 to a run position and operating the accelerator, a new vehiclerun, that is, a new trip, is started. This trip is ended by, forexample, the off-operation of the key, the re-depression of the powerswitch ST_ON, etc.

If it is determined by the vehicle run start determination device 146that the user's operation for starting to run the vehicle has beenperformed, the previous-trip abnormality determination device 148determines whether or not the information about the abnormality of thehigh speed step (second gear step) H determined to be present by theabnormality determination device 136 is stored, that is, whether or notthe abnormality of the high speed step H occurred during the previoustrip, that is, during the run preceding the present new start of vehiclerun, on the basis of whether or not the high-speed step abnormalitydetermination flag FHE is stored as the high-speed step determinationflag FH in the storage device 138.

At the time of a new start of vehicle run where it is determined by thevehicle run start determination device 146 that the user's operation forstarting to run the vehicle has been performed, if it is determined bythe previous-trip abnormality determination device 148 that theinformation about the abnormality of the high speed step (second gearstep) H is stored, the re-determination-purpose speed change stepestablishment device 144 causes the shift control device 132 toestablish the high speed step H in order to cause the abnormalitydetermination device 136 to perform re-determine the presence/absence ofthe abnormality of an element related to the formation of the high speedstep H.

The fail-safe process device 142, in addition to the foregoing function,performs the abnormality determination on the basis of the high-speedstep determination flag FH that has been set up again and thus updatedby the abnormality determination device 136, and accordingly executesthe fail-safe process.

The shift control device 132, in addition to the foregoing function,performs an operation for putting the vehicle into a ready-to-run stateby setting up the low speed step L after the fail-safe process isperformed by the fail-safe process device 142. Besides, even in the casewhere, at the time of a new start of vehicle run, it is determined bythe previous-trip abnormality determination device 148 that theinformation about the abnormality of the high speed step H is notstored, the shift control device 132 performs an operation for puttingthe vehicle into the ready-to-run state by setting up the low speed stepL.

In this manner, the re-determination-purpose speed change stepestablishment device 144, in response to the activating operation of thevehicle and prior to the setting of the ready-to-run state, forms thehigh speed step H and causes the re-determination of thepresence/absence of an abnormality of an element related to theformation of the high speed step H.

In this embodiment, the abnormality determination device 136, thestorage device 138, the re-determination-purpose speed change stepestablishment device 144, the previous-trip abnormality determinationdevice 148, etc., correspond to an abnormality determination device.

FIG. 10 is a flowchart illustrating portions of the control functions ofthe electronic control devices 28, 34 and 44, that is, an abnormalitydetermination routine for performing the abnormality determinationregarding the high speed step H. This routine is repeatedly executed ina very short cycle time of, for example, about several msec to severalten msec.

Firstly, in step (hereinafter, “step” will be omitted) S1 correspondingto the speed change step determination device 140, it is determinedwhether or not the shift of the transmission 22 to the high speed step H(second gear step) has been performed, for example, on the basis ofwhether or not the command values of the drive currents ISOL1 and ISOL2for obtaining the high speed step H have been output to the hydrauliccontrol circuit 50.

If a negative judgment is made in S1, this routine is ended. If anaffirmative judgment is made in S1, it is then determined whether or notthe switch SW1 is in the on-state, in S2 corresponding to theabnormality determination device 136. If an affirmative judgment is madein S2, it is then determined whether or not the switch SW2 is in theoff-state, in S3 corresponding to the abnormality determination device136. If an affirmative judgment is made in S3, it is then determinedwhether or not the switch SW3 is in the on-state, in S4 corresponding tothe abnormality determination device 136.

If an affirmative judgment is made in S4, the high-speed step normalitydetermination flag FHG is set up as the high-speed step determinationflag FH in S5 corresponding to the abnormality determination device 136.On the other hand, if a negative judgment is made in any one of S2 toS4, the high-speed step abnormality determination flag FHE is set up asthe high-speed step determination flag FH in S6 corresponding to theabnormality determination device 136.

Subsequently to S5 or S6, in S7 corresponding to the storage device 138,the high-speed step determination flag FH is stored while it is beingrewritten to the determination flag F set up in S5 or S6.

Furthermore, subsequently to S5 or S6, in a step (not shown)corresponding to the fail-safe process device 142, the command toprohibit the shift to the high speed step H is output if the high-speedstep abnormality determination flag FHE has been set up as thehigh-speed step determination flag FH. Then, if it is determined thatthere is an abnormality regarding the high speed step H, the vehicle isrun only on the low speed step L from then on. On the other hand, if thehigh-speed step normality determination flag FHG has been set up as thehigh-speed step determination flag FH, the command to prohibit the shiftto the high speed step H is not output. Then, if it is determined thatthe high speed step H is normal, the switch between the low speed step Land the high speed step H is performed, for example, from a shift chartshown in FIG. 9 on the basis of the state of the vehicle, from then on.

FIG. 11 is a flowchart illustrating portions of the control functions ofthe electronic control devices 28, 34 and 44, that is, a controloperation for performing the abnormality determination regarding thehigh speed step H which is a system check that is executed at the timeof start of vehicle run. This routine is repeatedly executed in a veryshort cycle time of, for example, about several msec to several tenmsec. The abnormality determination routine of FIG. 10 is a subroutinethat corresponds to the abnormality determination routine executed inthe flowchart of FIG. 11.

Firstly in step S11 corresponding to the vehicle run start determinationdevice 146, it is determined whether or not a user's operation forstarting to run the vehicle has been performed, for example, on thebasis of whether or not the power switch ST_ON has been operated in astate where the brake pedal is operated after the key has been insertedinto the key slot.

If a negative judgment is made in S11, this routine is ended. However,if an affirmative judgment is made in S11, the process proceeds to S12corresponding to the previous-trip abnormality determination device 148.In S12, it is determined whether or not an abnormality regarding thehigh speed step H occurred during the previous trip, for example, on thebasis of whether or not the high-speed step abnormality determinationflag FHE is stored as the high-speed step determination flag FH in S7 inFIG. 10.

If an affirmative judgment is made in S12, the process proceeds to S13corresponding to the re-determination-purpose speed change stepestablishment device 144. In S13, the high speed step H is establishedin order that the presence/absence of an abnormality of an elementrelated to the formation of the high speed step H will be re-determinedin the abnormality determination routine of FIG. 13.

Subsequently, in S14 corresponding to the abnormality determinationroutine shown in FIG. 10, the abnormality of the element related to theformation of the high speed step H is determined to be present, and thehigh-speed step determination flag FH is newly set up and thus updated.

Subsequently, in S15 corresponding to the fail-safe process device 142,the abnormality determination is performed on the basis of thehigh-speed step determination flag FH updated in S14.

If the high-speed step abnormality determination flag FHE is set up asthe high-speed step determination flag FH in S14 and an affirmativejudgment is made in S14, the command to prohibit the shift to the highspeed step H is output as a fail-safe process in S16 corresponding tothe fail-safe process device 142. Thus, the shift to the high speed stepH is prohibited beforehand, without the need to actually perform theshift to the high speed step H during the running of the vehicle.

If the high-speed step normality determination flag FHG has been set upas the high-speed step determination flag FH in S14 and a negativejudgment is made in S15, the command to prohibit the shift to the highspeed step H is not output, as a normal-time process, in S17corresponding to the fail-safe process device 142. Therefore, the shiftto the high speed step H is allowed during the running of the vehicle.

In the case where a negative judgment is made in S12, or subsequently toS16 or S17, an operation for putting the vehicle into the ready-to-runstate by setting up the low speed step L (1st speed gear step) in S18corresponding to the shift control device 132.

As described above, according to the embodiment, if the informationabout an abnormality of an element related to the formation of the highspeed step H which was determined to be present by the abnormalitydetermination device 136 is stored in the storage device 138 when thevehicle is to newly start to run, the high speed step H is establishedby the re-determination-purpose speed change step establishment device144 in order to cause the re-determination of the presence/absence ofthe abnormality of the element related to the formation of the highspeed step H. Therefore, the occurrence of the abnormality that cannotbe detected unless the high speed step H has actually been establishedcan be determined before the vehicle runs on the high speed step H.Therefore, for example, if the abnormality exists, the fail-safeoperation of prohibiting the shift to the high speed step H can beperformed. On the other hand, if normality has returned, the shift tothe high speed step H is allowed. Thus, the drivability can be improved.

Furthermore, the frequency of the abnormality determination beingperformed regarding the high speed step H, which is less frequentlyused, becomes higher, so that the drivability can be further improved.

Furthermore, in response to the activating operation of the vehicle andprior to the setting of the ready-to-run state, the transmission 22 iscaused to be in the high speed step H by the re-determination-purposespeed change step establishment device 144. Therefore, there is a needto set up the high speed step H and perform the abnormalitydetermination again beforehand only in the case where the informationabout the abnormality is stored. That is, it is no longer necessary toset up the high speed step H and perform the abnormality determinationevery time the vehicle is to newly start to run. Therefore, the lowspeed step L can be promptly set up, and the time required before thevehicle is put into the ready-to-run state is shortened, and thedrivability can be improved.

While the embodiment of the invention has been described in detail withreference to the drawings, the invention is also applicable in othermanners.

For example, although in the foregoing embodiment, the transmission 22is a two-step automatic transmission (speed reducer) having the lowspeed step L and the high speed step H which is provided between the MG2and the output shaft 14 so that the torque the MG2 outputs is increasedand then applied to the output shaft 14, the transmission 22 is notrestrictive, that is, the invention is also applicable if a differenttype of transmission is employed. For example, the invention is alsoapplicable if a well-known planetary gear type stepped (multi-step)transmission that transmits the output of the engine 24 to the drivingwheels 18 is employed.

Furthermore, although in the foregoing embodiment, the abnormalitydetermination device 136 performs the abnormality determinationregarding the speed change steps L, H in accordance with theon/off-states of the switches SW1, SW2, SW3, this determination methodis not restrictive, but other determination methods may also be used.For example, the abnormality determination regarding the speed changesteps L, H may be performed by performing the abnormality determinationregarding a break or shortcircuit of each of the first linear solenoidvalve SLB1 and the second linear solenoid valve SLB2 on the basis ofdetection signals supplied from well-known IC type abnormality detectionsensors such as a break detection sensor, a shortcircuit detectionsensor, etc.

While the invention has been described with reference to exemplaryembodiments thereof, it is to be understood that the invention is notlimited to the exemplary embodiments or constructions. To the contrary,the invention is intended to cover various modifications and equivalentarrangements. In addition, while the various elements of the exemplaryembodiments are shown in various combinations and configurations, whichare exemplary, other combinations and configurations, including more,less or only a single element, are also within the spirit and scope ofthe invention.

1. An abnormality determination device of a vehicle that includes astepped type automatic transmission capable of forming a plurality ofspeed change steps, comprising: an abnormality determiner thatdetermines presence/absence of an abnormality of an element related toformation of a predetermined speed change step in a state of the vehiclewhere the predetermined speed change step is formed; a storage devicethat stores information about the abnormality determined to be presentby the abnormality determiner; and a controller that establishes, if theinformation about the abnormality is stored in the storage device whenthe vehicle is to newly start to run, the predetermined speed changestep where the abnormality stored occurred, in order to causere-determination of the presence/absence of the abnormality of theelement related to the formation of the predetermined speed change step.2. The abnormality determination device of the vehicle according toclaim 1, wherein the stepped type automatic transmission is capable offorming one or more speed change steps on a low speed step side, and oneor more speed change steps on a high speed step side, and wherein if theinformation about the abnormality stored in the storage device isinformation about an element related to the formation of a speed changestep on the high speed step side, the controller forms the speed changestep on the high speed step side and causes the abnormality determinerto re-determine the presence/absence of the abnormality of the elementrelated to the formation of the speed change step on the high speed stepside when the vehicle is to newly start to run.
 3. The abnormalitydetermination device of the vehicle according to claim 2, wherein thevehicle is a hybrid vehicle, and wherein the controller causes thestepped type automatic transmission to be in the speed change step onthe high speed step side in response to an activating operation of thehybrid vehicle and prior to setting of a ready-to-run state of thevehicle.
 4. The abnormality determination device of the vehicleaccording to claim 2, wherein the speed change steps on the low speedstep side consist of only one low speed step, and the speed change stepson the high speed step side consist of only one high speed step, andwherein if the information about the abnormality stored in the storagedevice is information about the element related to the formation of thehigh speed step, the controller forms the high speed step and causes theabnormality determiner to re-determine the presence/absence of theabnormality of the element related to the formation of the high speedstep when the vehicle is to newly start to run.
 5. The abnormalitydetermination device of the vehicle according to claim 4, wherein thevehicle is a hybrid vehicle, and wherein the controller causes thestepped type automatic transmission to be in the high speed step inresponse to the activating operation of the hybrid vehicle and prior tothe setting of the ready-to-run state of the vehicle.
 6. An abnormalitydetermination method of a vehicle that includes a stepped type automatictransmission capable of forming a plurality of speed change steps,comprising: determining presence/absence of an abnormality of an elementrelated to formation of a predetermined speed change step in a state ofthe vehicle where the predetermined speed change step is formed; storinginformation about the abnormality determined to be present; andestablishing, if the information about the abnormality is stored whenthe vehicle is to newly start to run, the predetermined speed changestep where the abnormality stored occurred, and re-determining thepresence/absence of the abnormality of the element related to theformation of the predetermined speed change step.
 7. The abnormalitydetermination method of the vehicle according to claim 6, wherein thestepped type automatic transmission is capable of forming one or morespeed change steps on a low speed step side, and one or more speedchange steps on a high speed step side, and wherein if the storedinformation about the abnormality is information about an elementrelated to the formation of a speed change step on the high speed stepside, the speed change step on the high speed step side is formed andthe presence/absence of the abnormality of the element related to theformation of the speed change step on the high speed step side isre-determined when the vehicle is to newly start to run.
 8. Theabnormality determination method of the vehicle according to claim 7,wherein the vehicle is a hybrid vehicle, and wherein the stepped typeautomatic transmission is caused to be in the speed change step on thehigh speed step side in response to an activating operation of thehybrid vehicle and prior to setting of a ready-to-run state of thevehicle.
 9. The abnormality determination method of the vehicleaccording to claim 7, wherein the speed change steps on the low speedstep side consist of only one low speed step, and the speed change stepson the high speed step side consist of only one high speed step, andwherein if the stored information about the abnormality is informationabout the element related to the formation of the high speed step, thehigh speed step is formed and the presence/absence of the abnormality ofthe element related to the formation of the high speed step isre-determined when the vehicle is to newly start to run.
 10. Theabnormality determination method of the vehicle according to claim 9,wherein the vehicle is a hybrid vehicle, and wherein the stepped typeautomatic transmission is caused to be in the high speed step inresponse to the activating operation of the hybrid vehicle and prior tothe setting of the ready-to-run state of the vehicle.